Preparation of cyclooctatriene



. -2-;6'44 ,8 1'8 1 PREPARATIO "CF CYCI OQQ'EATRQRE Louis E.- Craig, Washington, N. J., assignor to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application September 29, 1950, Serial No. 187,674

3 Claims. (01. 260-666) Thi invention relates to an {improved process is isomerized by alkaline reagents to the 1,3,5- for the preparation of cyclooctatriene by reducisomer, the proportions of the isomers in the tion of cyclooctatetraene. Inaccordance with the product obtained by this process may vary. previously known procedure, cyclooctatriene'was In carrying out the process of the invention,

produced by reaction of cyclooctatetraene with 5 the initial concentration of cyclooctatetraene in lithium in ethylether to form a lithium adduct ammonia can vary, but is preferably from 5 to and the latter yielded cyclooctatriene upon reac- 25%. The temperature during the reduction is tion with an alcohol. advantageously maintained at 60 to 33 C.

I have discovered that cyclooctatetraene can (i. e., the boiling point of ammonia) so that the be more readily converted to cyclooctatriene by reaction can be carried out at atmospheric presreduction with an alkali metal such as sodium, sure. However, if superatmospheric pressure is lithium or potassium, in liquid ammonia. The applied, higher temperatures can be used, e. g. ammonia can be readily evaporated from the reup to about 0 C.

duction mixture, and the alkali metal compounds The alkali metal employed can be sodium, po-

(e. g., amides) as Well as any excess alkali metal, tassium or lithium. The amount of this reagent can be destroyed, for example, by treatment with v should be at least 2 atomic equivalents per mol an alcohol or another reagent adapted to undergo of cyclooctatetraene, an excess of at least mild reaction with the alkali metal and its amides. being preferably used. It is noted that despite By washin the residue thus obtained with water, the large excess of sodium employed in the foreend fractional distillation, cyclooctatr-iene (more going example, the reduction did not proceed be-f specifically, a mixture of 1,3,5- and 1,3,6-cycloyondthe triene stage. Lesser amounts of sodium, octatriene) is obtained in ood yield. e. to parts, can be used in the example My process is illustrated by the following exto produce a similar yield. ample, wh r in parts a by weight, In order to destroy and decompose alkali metal Example amides and excess alkali metal in the residue of the reduction mixture, an alcohol such as meth- 52 parts of cyclooctatetraene were dissolved i anol or ethanol is advantageously employed. 600 pa ts of liquid ammonia maintained at about However, other compounds such as ammonium 33 C., and 55 par s of metallic sodium in the chloride or bromide, or ammonolysis catalysts form of small fragments were added over a period 30 such as iron, sodium nitrate or mercury can be of about 5 hours, while agitating the mixture. u ed inst ad, The ammonia was then allowed to evaporate, and The cyclooctatriene obtained in accordance 700 parts of ethanol were added slowly over a with this invention is valuable for further synperiod of several hours. The mixture was then thesis, such as formation of Diels-Alder adducts,

heated to boiling under reflux for 2 hours, cooled, 5 homopolymers and copolymers, oxidation prodand poured into 500 parts of water. The resultuct-s such as peroxides, and other cyclooctane ing mixture was extracted exhaustively with d ivativ 7 petroleum ether, and the combined extracts dried Variations and modifications which will be obover anhydrous sodium sulfate. ,The petroleum vious to those skilled in the art can. be made in ether Was distilled ofi, and the residue fractionthe process specifically described without departally distilled under reduced pressure. 35 parts of ing from the spirit or scope of the invention.

a colorless distillate boiling at 87 to 87.5 .C. at I I claim:

an absolute pressure of 110 mm. of mercury were 1. A process for the production of cyclooctarecovered. This product absorbed 3 mols of hytriene which comprises reducing cyclooctatetradrogen on exhaustive hydrogenation, thus indiene with an alkali metal in the presence of liquid cating that it consisted essentially of cycloootaammonia. triene. Examination of the ultra-violet spectrum 2. A process for the production of cyclooctaof the product indicated it to be a mixture of triene, which comprises reducing 1 mol of cyclothe 1,3,5- and the 1,3,6- isomers, the former preoctatetraene with at least 2 atomic equivalents dominating. On redistillation, a product was of an alkali metal in excess liquid ammonia, at obtained having a refractive index (N of a temperature from 60 to 33 0., evaporat- 1.5 163. A maleic anhydride adduct of the proding the ammonia from the mixture, decomposing uct was also prepared, having a melting point the resulting alkali metal amides and destroying of 139 to 141 C. excess alkali metal in the residue, and recovering Since it has been found that the 1,3,6- isomer .cyclooctatriene from the resulting mixture.

3 4 3. A process for the production of cyclooctatriene, which comprises reducing 1 mol at cyclo- References Cited in the fi of s p nt octatetraene with at least 2.2 atomic equivalents Kmnsky et a1" n AcacL SOL URSS (1938) of sodium in liquid ammonia at atmospheric pp 0 and 1072 abstracted 1;; h b t a t pressure, the initial concentration of cycloocta- 5 VOL 33 5 33 tetraene in liquid ammonia being from 5 to polymerization of Acetylene 1-, COT, FIAT 25%. vapo ti the ammonia o the reduc- Final Report 967 (PB 62,593), p. 49, available tion mixture, decomposing the resulting sodamide May 23 947 and destroying excess sodium by treatment with Cope et; al., Jour. Am. Chem. Soc., vol. 72, an alcohol, and recovering cyclooctatriene from 10 25 54 m June 1950, received o b b 15, the resulting mixture. 1949).

LOUIS E. CRAIG. 

1. A PROCESS FOR THE PRODUCTION OF CYCLOOCTATRIENE WHICH COMPRISES REDUCING CYCLOOCTATETRAENE WITH AN ALKALI METAL IN THE PRESENCE OF LIQUID AMMONIA. 